1. Field of the Invention
The present invention relates to a projector which includes a laser light emitter.
2. Description of the Related Art
In these days, data projectors are used on many occasions as image projection apparatuses which project images including images of screens and video images of personal computers, as well as images based on image data which is stored in memory cards on to a screen. These projectors are such that light emitted from a light source is collected to a micromirror device called DMD (Digital Micromirror Device) or a liquid crystal plate for display of a color image onto the screen.
Conventionally, the mainstream of these projectors has been those which use a high-intensity discharge lamp as a light source. However, in recent years, there have been made many developments and proposals on projectors which use, as a light emitting element of a light source, a light emitting diode (LED), a laser light emitter, a semiconductor light emitting device such as a device utilizing organic EL, technology or a luminescent material which absorbs excitation light to emit light of a predetermined wavelength.
As a projector which uses a laser light emitter, for example, Japanese Unexamined Patent Publication No. 2003-295319 (JP-A-2003-295319) proposes a light source unit in which coherent light emitted from a laser light emitter is converted into incoherent light by a luminescent material or a diffusion plate and the resulting incoherent light is emitted to the outside of the projector, whereby any laser beam is prevented from being emitted directly to the outside as light source light.
In a projector like this, safety is increased by adding a safety device for switching off the laser light emitter when the fall or detachment of the luminescent material or the diffusion plate is detected or disposing an additional diffusion plate on an optical path of the incoherent light. Consequently, in this projector, when the luminescent material or the diffusion plate falls, the safety device is activated to stop the emission of laser light from the laser light emitter momentarily, or laser light is prevented from leaking out as it is by the auxiliary diffusion plate. Thus, the time during which laser light is shone to other positions than the predetermined position or leaks out is made as short as possible to thereby ensure the safety of the projector.
However, when the safety of the projector is ensured by incorporating in the projector the safety device which detects the fall or detachment of the luminescent material or the diffusion plate so as to prevent laser light from not being converted into luminescent light or diffusion light or by adding the diffusion plate, space for the safety device and the diffusion plate needs to be secured and the parts need to be added, leading to a problem with miniaturization of the projector and a problem of increased costs due to involving the additional labor hours in fabrication of the projector.